A few tips, not sure if they are the problem.
Basics, current DirectX and Video drivers.
Rock looks him up and down. Ah he looks like a Warbirds player, probably has those covered.
If you have a VooDoo card make sure you don't have 32bit checked in the video setup. You might try deleting the video.cfg file in the Aces High\settings folder and go back to video setup to redo it if your current settings are so far outa wack you can't get to the setup screen. Or if you've never been to video setup now would be a good time.
Some times when I choose online AH seems to have locked up. H2H would act the same way since it's online too. If the front end has trouble connecting to the server it will appear to lock up but, will timeout after a bit(about a minute) and tell you it can't connect.
Hope that helps get you pointed in the right direction.